Compositions and methods of using propylene sulfide-based polymers for treatment of Chagas disease

ABSTRACT

The present invention provides novel nanostructures comprising solution of PPSU20. Methods of preparing the novel PPSU nanostructures, and applications of such nanostructures are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.62/880,013, filed Jul. 29, 2019, the contents of which are incorporatedby reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

This invention was made with government support under grant numbersAI144529 and HL132390 awarded by the National Institutes of Health. Thegovernment has certain rights in the invention.

REFERENCE TO A SEQUENCE LISTING SUBMITTED VIA EFS-WEB

The content of the ASCII text file of the sequence listing named“702581_01793_ST25.txt” which is 0.751 kb in size was created on Jul.28, 2020 and electronically submitted via EFS-Web herewith theapplication is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

American Trypanosomiasis or Chagas disease (CD) is a vector-bornedisease first described by the Brazilian sanitary physician CarlosChagas, in 1909. After discovering the flagellate protozoan parasite,Trypanosoma cruzi, in sylvatic and domestic animals, human blood, and inthe triatomine insect vector (“kissing” bug), Chagas deduced theessential aspects of the disease. At the beginning of the 20th century,CD was considered a rural endemic disease, strictly associated with theproximity between the insect vector and humans living in poor housingand sanitary conditions in rural areas of Latin America. However, in the21st century, CD has spread to non-endemic areas, such as Canada, theUSA, Europe, Australia, and Japan due to population migrations and thealtered distribution and proliferation of triatomine bugs stimulated byclimate change. As no vaccine is currently available, 65-100 millionpeople live at risk of contracting a T. cruzi infection. Of those atrisk, around 6-7 million people are infected and approximately 14,000deaths are reported annually in endemic and non-endemic countries. Thesedeaths typically occur as a consequence of heart failure induced by theT. cruzi infection. This alarming data is reflected in the CD status asa “neglected disease”, which is still overlooked by drug developers asit mostly affects poor people in low-income countries.

Since 1912, several molecules have been experimentally tested againstCD, from primitive arsenic and mercury derivatives to antibiotics, andmore recently ergosterol synthesis inhibitors, all without successfulresults. Only two hydrophobic nitroimidazole pro-drugs, Benznidazole(BNZ) and Nifurtimox (Nfx), have been available to treat T.cruzi-infected patients since 1970. Despite the poor bioavailability andpermeability, both drugs can reach up to 80% of efficacy when usedduring acute T. cruzi infections. However, the requirement for long-termtreatment and the severe side effects, including allergic dermatitis,pruritus, gastrointestinal manifestations, and neuropathy, lead to thepermanent withdrawal of treatment in 6 to 40% of patients receiving Nfxand 7 to 30% of those receiving BNZ.

There is a need for a Chagas treatment that is effective in treating T.cruzi infections without the severe side effects shown in the presenttreatment available treatments.

SUMMARY OF THE INVENTION

The present disclosure provides novel nanocarriers for treating Chagasdisease. The nanocarriers comprise (a) poly(ethyleneglycol)-block-poly(propylene sulfide) copolymers and (b) a therapeuticagent for treating Chagas disease. The therapeutic agent is selectedfrom the group consisting ofN-benzyl-2-(2-nitro-1H-imidazol-1-yl)acetamide (Benznidazole),N-(3-Methyl-1,1-dioxido-4-thiomorpholinyl)-1-(5-nitro-2-furyl)methanimine(Nifurtimox),1-Methyl-2-{[4-methylsulfanyl)phenoxy]methyl}-5-nitro-1H-imidazole(Fexinidazole),4-[4-[4-[4-[[(3R,5R)-5-(2,4-difluorophenyl)tetrahydro-5-(1H-1,2,4-triazol-1-ylmethyl)-3-furanyl]methoxy]phenyl]-1-piperazinyl]phenyl]-2-[(1S,2S)-1-ethyl-2-hydroxypropyl]-2,4-dihydro-3H-1,2,4-triazol-3-one(Posaconazole), cysteine protease inhibitors, parasite proteasomeinhibitors such asN-[4-fluoro-3-(6-pyridin-2-yl-[1,2,4]triazolo[1,5-a]pyrimidin-2-yl)phenyl]-2,4-dimethyl-1,3-oxazole-5-carboxamide.

In another aspect, the disclosure provides a pharmaceutical compositioncomprising the nanocarrier described herein and one or morepharmaceutically acceptable excipients.

In a further aspect, the disclosure provides a method of treating aTrypanosoma cruzi infection in a subject in need thereof, the methodcomprising administering to the subject a therapeutically effectiveamount a pharmaceutical composition comprising a nanocarrier comprisingpoly(ethylene glycol)-block-poly(propylene sulfide) copolymer; and atherapeutic agent for treating Chagas disease.

12. The method of claim 11, wherein the therapeutic agent for treatingChagas disease is selected from the group consisting ofN-benzyl-2-(2-nitro-H-imidazol-1-yl)acetamide (Benznidazole),N-(3-Methyl-1,1-dioxido-4-thiomorpholinyl)-1-(5-nitro-2-furyl)methanimine(Nifurtimox),1-Methyl-2-{[4-methylsulfanyl)phenoxy]methyl}-5-nitro-1H-imidazole(Fexinidazole),4-[4-[4-[4-[[(3R,5R)-5-(2,4-difluorophenyl)tetrahydro-5-(1H-1,2,4-triazol-1-ylmethyl)-3-furanyl]methoxy]phenyl]-1-piperazinyl]phenyl]-2-[(1S,2S)-1-ethyl-2-hydroxypropyl]-2,4-dihydro-3H-1,2,4-triazol-3-one(Posaconazole), cysteine protease inhibitors, parasite proteasomeinhibitors such asN-[4-fluoro-3-(6-pyridin-2-yl-[1,2,4]triazolo[1,5-a]pyrimidin-2-yl)phenyl]-2,4-dimethyl-1,3-oxazole-5-carboxamide.

The foregoing and other aspects and advantages of the invention willappear from the following description. In the description, reference ismade to the accompanying drawings which form a part hereof, and in whichthere is shown by way of illustration a preferred embodiment of theinvention. Such embodiment does not necessarily represent the full scopeof the invention, however, and reference is made therefore to the claimsand herein for interpreting the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

FIG. 1 Benznidazole polymersomes are 100 nm particles with good in vitrostability. (A) Benznidazole (BNZ) was loaded into polymersomes (BNZ-PS)by the thin film hydration method. (B) Representative cryo transmissionelectron microscopy images of PS and BNZ-PS. (C) The diameters of PS andBNZ-PS are approximately 100 nm as determined by dynamic lightscattering analysis. (D) The stability of BNZ-PS was determined byincubating the particles in PBS at room temperature and subtracting thefraction of BNZ found free in solution over time.

FIG. 2 Benznidazole polymersomes are more potent than free benznidazoleagainst T. cruzi in vitro. (A) In vitro killing of purifiedtrypomastigote and amastigote forms of T. cruzi by BNZ and BNZ-PS.Amastigotes and trypomastigotes were purified from infected H9C2 cellcultures and tested in a 24 h resazurin cell viability assay usingincreasing doses of BNZ or BNZ-PS. (B) PS are readily taken up by T.cruzi-infected H9C2 cells. H9C2 cells were infected with T. cruziexpressing Luc-mNeonGreen (green) for 24 h and Alexa630-labeled PS(yellow) were added and cultures incubated for an additional 24 h. Cellswere imaged after staining with DAPI (blue) and Cell Mask Deep Red Dye(purple). (C) BNZ-PS are significantly more potent against intracellularT. cruzi than free BNZ. Cells were cultured and treated as in B, butwith different concentrations of BNZ or BNZ-PS, and imaged after DAPIand Cell Mask staining. The key images for comparison are the left (T.cruzi) BNZ and BNZ-PS panels at each drug concentration.

FIG. 3 . Benznidazole polymersomes are more potent than freebenznidazole against T. cruzi in vivo. (A) Effective suppression ofparasitemia by BNZ and BNZ-PS. Mice were infected with T. cruzi at d0and treated with BNZ or various doses of BNZ-PS after parasitemia hadreached approximately 2×10⁵ ml⁻¹ on d7. Parasitemia was monitored everyfew days through the end of the experiment on d25. (B) Mice weresacrificed at the end of the experiment and cardiac parasitosis wasquantitated by qPCR. (C) Cardiac inflammation was quantitated in heartsections two ways—by total cellularity and by the percentage of cellulararea occupied by nuclei. (D) Representative cardiac histology at the endof the experiment. Bar=100 μM.

FIG. 4 . Benznidazole polymersomes are much less toxic than freebenznidazole. Mice were treated with BNZ (100 mg/kg) or BNZ-PS (1.5 or0.15 mg/kg), plus controls. (A) Mice treated with BNZ, but not BNZ-PS,lose weight during 3 weeks of treatment. Weights were determined everyfew days. (B) Mice treated with BNZ show hepatotoxicity as reflected byincreased serum ALT at d21. Serum ALT was also measured and did not showsignificant elevation in any mouse.

FIG. 5 Validation of BNZ loading within BNZ-PS. (A) Representativechromatogram and (B) positive ion mass spectrum of BNZ standards. TheBNZ peak is indicated at m/z of ˜261. (C) Calibration curve of BNZstandards. (D) Representative chromatogram of BNZ-PS displaying a BNZpeak at the same elution time as in the standard (A).

DETAILED DESCRIPTION OF THE INVENTION

The present invention has been described in terms of one or morepreferred embodiments, and it should be appreciated that manyequivalents, alternatives, variations, and modifications, aside fromthose expressly stated, are possible and within the scope of theinvention.

The present disclosure describes nanocarriers for treating Chagasdisease. The nanocarriers comprise poly(ethyleneglycol)-block-poly(propylene sulfide) copolymer and a therapeutic agentfor treating Chagas disease.

Chagas disease, or American trypanosomiasis, is a tropical parasiticdisease caused by the protozoan Trypanosoma cruzi. It is spread mostlyby insects known as triatominae or kissing bugs. These insects are knownby a number of local names, including: vinchuca in Argentina, Bolivia,Chile and Paraguay, barbeiro (the barber) in Brazil, pito in Colombia,chinche in Central America, and chipo in Venezuela. The disease may alsobe spread through blood transfusion, organ transplantation, eating foodcontaminated with the parasites, and by vertical transmission (from amother to her fetus). Diagnosis of early disease is by finding theparasite in the blood using a microscope. Chronic disease is diagnosedby finding antibodies for T. cruzi in the blood.

The term “nanocarrier” refers to a nanomaterial used as a transportmodule for another substance. For example, the nanocarriers disclosedherein may be used as a transport module for therapeutic agents fortreating Chagas disease. The nanocarriers disclosed herein may be usedas components of pharmaceutical compositions for treating Chagasdisease. In some embodiments, the nanocarriers disclosed herein arecomposed of a poly(ethylene glycol)-block-poly(propylene sulfide)copolymer and a therapeutic agent for treating Chagas disease.

Poly(ethylene glycol)-block-poly(propylene sulfide) copolymers(PEG-b-PPS) can be prepared via known methods, for example thosedescribed in Allen, S. et al., Facile assembly and loading oftheranostic polymersomes via multi-impingement flash nanoprecipitationJ. Control. Release 2017. 262: p. 91-103 and in U.S. Pat. No.10,633,493, each of which is incorporated herein by reference in itsentirety with regard to the method of preparing the copolymers. Anexemplary synthesis is described in the Examples. For example, thePEG-b-PPS are prepared via the anionic ring-opening polymerization ofpropylene sulfide initiated by PEG thioacetate and end-capped with PEGmesylate. The PEG-b-PPS are purified by precipitation in methanol.

To obtain the nanocarriers described herein, the PEG-b-PPS are loadedwith a therapeutic agent for treating Chagas disease. The nanocarrierscan be prepared/loaded, for example, by any viable method ofnanoparticle fabrication and/or self-assembly, including thin filmrehydration, flash-nanoprecipitation, microfluidics, or solventextraction To load the PEG-b-PPS with a therapeutic agent, via thin filmrehydration, the PEG-b-PPS are dissolved with therapeutic agents in oneor more organic solvents. The resulting solution is dehydrated by addingan aqueous solution (e.g., a buffer such as phosphate-buffered saline)to the mixture which can be shaken overnight, followed by extrusion(e.g., using a syringe filter). Unloaded therapeutic agents can beremoved either via exclusion column purification or dialysis.

Nanocarriers can be characterized for size distribution via dynamiclight scattering (DLS) and nanoparticle tracking analysis (NTA), and formorphology via cryogenic transmission electron microscopy (cryoTEM).Therapeutic agent loading and encapsulation efficiencies can becharacterized via liquid chromatography mass spectrometry.

A variety of types of nanocarriers can be prepared by varying the degreeof propylene sulfide polymerization, oxidation or branching. Forexample, nanocarriers may be in the form of polymersomes (PEG weightfraction of about 0.25 to about 0.45), micelles (PEG weight fractionabove 0.45), biocontinuous nanospheres (PEG weight fraction below 0.25),filomicelles (PEG weight fraction of about 0.35 to about 0.45),polypropylene sulfone nanogels (above 90% oxidized PPS homopolymer), orpolymersomes assembled from branched raft polymerizedpoly(oligo(ethylene glycol) methyl ethermethacrylate)-b-poly(oligo(propylenesulfide) methacrylate)(POEGMA-POPSMA¹⁻⁵ In some embodiments, the block copolymer has a PEGweight fraction of about 0.36.

In some embodiments, the nanocarrier is a polymersome having an aqueouscore and hydrophobic and hydrophilic regions of the lipid bilayersurrounding the aqueous core. The polymersome nanocarrier can have a PEGweight fraction of about 0.25 to about 0.45, e.g., 0.36. The polymersomenanocarrier may have a diameter of about 10 nm to about 300 nm,alternatively from about 30 nm to about 150 nm in diameter,alternatively from about 30 nm to about 60 nm, alternatively from about60 nm to about 90 nm, alternatively from about 100 nm to about 150 nm indiameter. In some embodiments, the size of the polymersome remains aboutthe same when it is loaded with a Chagas therapeutic agent compared tothe size of an unloaded polymersome made from the same copolymer. In oneembodiment, the polymersome comprises a vesicular polymer membranecomposed of PEG₁₇-PPS₆₀-PEG₁₇.

In some embodiments, the nanocarrier is a bicontinuous nanosphere (BCN)characterized by two continuous phases; (i) a cubic lattice of aqueouschannels that traverse (ii) an extensive hydrophobic interior volume.Based on small angle X-ray scattering (SAXS) analysis, BCN haveprimitive type cubic internal organization (Im3m) as confirmed by Braggpeaks with relative spacing ratios at √2, √4, and √6. BCNs are thepolymeric equivalent of lipid cubosomes and are lyotropic. BCN canincorporate both hydrophobic and hydrophilic therapeutic agents. BCNscan be prepared via known methods, for examples those described inAllen, S. et al., Benchmarking bicontinuous nanospheres againstpolymersomes for in vivo biodistribution and dual intracellular deliveryof lipophilic and water soluble payloads. ACS Appl. Mater. Interfaces2018, 10, 40, 33857-33866, which is incorporated herein by reference.

In some embodiments, the nanocarrier is a micelle or a filomicellehaving a hydrophobic/lipophilic core and a hydrophilic exterior. Micelleor filomicelle nanocarriers have a spherical morphology and aretypically smaller (e.g., less than 50 nm) than polymersomes and thehydrophobic core can be loaded with a therapeutic agent. The micellessuitably have a PEG weight fraction of about 0.35 to about 0.45.Micelles or filomicelles can be prepared via known methods, for examplethose described in Karabin, N. B. Allen, S., Kwon, H. et al. Sustainedmicellar delivery via inducible transitions in nanostructure morphology.Nat Commun 9, 624 (2018), which is incorporated herein by reference.

Other suitable preparation methods of the nanocarriers disclosed hereincan be prepared via known methods, e.g., Du, F., et al., (2019).Homopolyner Self-Assembly via Poly(propylene Sulfone) Networks.ChemRxiv. Preprint; Du F. et a., Sequential intracellular release ofwater-soluble cargos from Shell-crosslinked polymersomes. J ControlRelease. 2018; 282:90-100; and Yj S., et al, Tailoring NanostructureMorphology for Enhanced Targeting of Dendritic Cells in Atherosclerosis.ACS Nano. 2016; 10(12):11290-11303, each of which are incorporatedherein by reference in their entirety.

The nanocarrier further comprises a therapeutic agent for treatingChagas disease. The therapeutic agent may be selected from the groupconsisting of N-benzyl-2-(2-nitro-TH-imidazol-1-yl)acetamide(Benznidazole) andN-(3-Methyl-1,1-dioxido-4-thiomorpholinyl)-1-(5-nitro-2-furyl)methanimine(Nifurtimox). In some embodiments, the therapeutic agent may be selectedfrom the group consisting ofN-benzyl-2-(2-nitro-H-imidazol-1-yl)acetamide (Benznidazole),N-(3-Methyl-1,1-dioxido-4-thiomorpholinyl)-1-(5-nitro-2-furyl)methanimine(Nifurtimox),1-Methyl-2-{[4-methylsulfanyl)phenoxy]methyl}-5-nitro-TH-imidazole(Fexinidazole),4-[4-[4-[4-[[(3R,5R)-5-(2,4-difluorophenyl)tetrahydro-5-(1H-1,2,4-triazol-1-ylmethyl)-3-furanyl]methoxy]phenyl]-1-piperazinyl]phenyl]-2-[(1S,2S)-1-ethyl-2-hydroxypropyl]-2,4-dihydro-3H-1,2,4-triazol-3-one(Posaconazole), cysteine protease inhibitors, parasite proteasomeinhibitors such asN-[4-fluoro-3-(6-pyridin-2-yl-[1,2,4]triazolo[1,5-a]pyrimidin-2-yl)phenyl]-2,4-dimethyl-1,3-oxazole-5-carboxamide(GNF6702). In some embodiments, the therapeutic agent isN-benzyl-2-(2-nitro-1H-imidazol-1-yl)acetamide (Benznidazole). Theinventors have surprisingly found that encapsulation of the therapeuticagent for treating Chagas disease can be administered at substantiallylower levels than the free form drug, reducing unwanted and unnecessaryside effects, allowing for longer term use of the treatment.

The nanocarrier may comprise any suitable molar ratio of therapeuticagent:core necessary to achieve the desired effect. For example, thenanocarrier may comprise a molar ratio of therapeuticagent:poly(ethylene glycol)-block-poly(propylene sulfide) copolymer of0.001%-50%. For example, the molar ratio may be 0.001%, 0.005%, 0.01%,0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 20%, 30%, 40%, or 50%. Insome embodiments, the molar ratio of therapeutic agent:poly(ethyleneglycol)-block-poly(propylene sulfide) copolymer is 1%-10%. %. Inparticular embodiments, the molar ratio of therapeuticagent:poly(ethylene glycol)-block-poly(propylene sulfide) copolymer is1%.

In some embodiments, the nanocarriers present an encapsulationefficiency (% EE) of greater than 0% to about 100%. In some embodiments,the nanocarriers present an encapsulation efficiency (% EE) of about 20%to about 40%. In some embodiments, the nanocarriers present a loadingefficiency (% LE) of greater than 0% to 100%. In some embodiments, thenanocarriers present a % LE of about 0.5 to about 2% w/w.

In some embodiments, nanocarriers comprising the therapeutic agentBenznidazole may enable delivery of significantly lower therapeuticallyeffective dosages of Benznidazole compared to the dosages required fortherapeutic efficacy of Benznidazole alone. For example, a typical freeBenznidazole IC₅₀ may be about 33 μM. Benznidazole loaded in nanocarrierformulations has an estimated IC₅₀ of 3.5 μM, a concentration nearly 10times lower. In a subject, while Benznidazole may typically beadministered at a dosage of about 100 mg/kg, loaded-Benznidazolenanocarrier of the present invention can be administered at a dosagebetween about 0.025 mg/kg and about 2 mg/kg (For example, FIG. 5A). Insome embodiments, the loaded-Benznidazole nanocarrier can beadministered at a dosage of 0.025 mg/kg to 100 mg/kg. In someembodiments, the loaded-Benznidazole nanocarrier can be administered ata dosage of 0.025 mg/kg, or 0.03 mg/kg, or 0.05 mg/kg, or 0.10 mg/kg, or0.15 mg/kg, or 0.30 mg/kg, to 0.5 mg/kg, or 0.75 mg/kg, or 1.0 mg/kg, or1.25 mg/kg, or 1.5 mg/kg, or 1.75 mg/kg, or 2.0 mg/kg. In someembodiments, the loaded-Benznidazole nanocarrier can be administered ata dosage of 2.0 mg/kg, or 5.0 mg/kg, or 10 mg/kg, or 20 mg/kg, or 30mg/kg, or 40 mg/kg, or 50 mg/kg, or 60 mg/kg, or 70 mg/kg, or 80 mg/kg,or 90 mg/kg, or 100 mg/kg. In some embodiments, the lowertherapeutically effective dose of Benznidazole when administered in ananocarrier formulation is at least 500, at least 1000, at least 10,000,at least 25,000, or at least 50,000 times lower than the therapeuticallyeffective dose of free Benznidazole (when administered orally). Inaccordance with such embodiments, nanocarriers comprising Benznidazolemay be safely used in a subject with improved efficacy and safety.

In some embodiments, the loaded-Nifurtimox nanocarrier can beadministered at a dosage of 0.025 mg/kg to 100 mg/kg. In someembodiments, the loaded-Nifurtimox nanocarrier can be administered at adosage of 0.025 mg/kg, or 0.03 mg/kg, or 0.05 mg/kg, or 0.10 mg/kg, or0.15 mg/kg, or 0.30 mg/kg, to 0.5 mg/kg, or 0.75 mg/kg, or 1.0 mg/kg, or1.25 mg/kg, or 1.5 mg/kg, or 1.75 mg/kg, or 2.0 mg/kg. In someembodiments, the loaded-Nifurtimox nanocarrier can be administered at adosage of 2.0 mg/kg, or 5.0 mg/kg, or 10 mg/kg, or 20 mg/kg, or 30mg/kg, or 40 mg/kg, or 50 mg/kg, or 60 mg/kg, or 70 mg/kg, or 80 mg/kg,or 90 mg/kg, or 100 mg/kg. In some embodiments, the lowertherapeutically effective dose of Nifurtimox when administered in ananocarrier formulation is at least 500, at least 1000, at least 10,000,at least 25,000, or at least 50,000 times lower than the therapeuticallyeffective dose of free Nifurtimox (when administered orally). Inaccordance with such embodiments, nanocarriers comprising Nifurtimox maybe safely used in a subject with improved efficacy and safety.

In some embodiments, the nanocarriers comprising the therapeutic agentare able to achieve the same immunomodulatory effects at a lowertherapeutically effective dose compared the therapeutically effectivedose required for free therapeutic agent (i.e. the therapeutic agent inthe absence of the nanocarrier), therefore allowing therapeutic efficacywith minimized or null side effects in the subject. Side effectstypically associated with Chagas disease treatments may include, but arenot limited to, neuropathy, dermatitis, pruritus, gastrointestinalmanifestations, anorexia, bone marrow suppression, headache, weightloss, hepatic function alteration, among others.

The disclosed nanocarriers are advantageous over current therapies onthe market for a variety of reasons. The polymers used in thenanocarriers, poly(ethylene glycol) and poly(propylene sulfide) havebeen widely proven to be inert.

The nanocarriers disclosed herein may also be incorporated intopharmaceutical compositions. The disclosed nanocarriers orpharmaceutical compositions comprising the same may be used in methodsof treating Chagas disease in a subject in need thereof. Thepharmaceutical compositions may further comprise one or morepharmaceutically acceptable excipients. The pharmaceutically acceptableexcipients will be dependent on the mode of administration to be used.Suitable modes of administration include, without limitation: topical,subcutaneous, transdermal, intradermal, intralesional, intraarticular,intraperitoneal, intravesical, transmucosal, gingival, intradental,intracochlear, transtympanic, intraorgan, epidural, intrathecal,intramuscular, intravenous, intravascular, intraosseus, periocular,intratumoral, intracerebral, and intracerebroventricular administration.In some embodiments, the disclosed pharmaceutical compositions areadministered parenterally. In some embodiments, parenteraladministration is by intrathecal administration, intracerebroventricularadministration, or intraparenchymal administration. In particularembodiments, the disclosed pharmaceutical compositions are administeredsubcutaneously. In particular embodiments, the disclosed pharmaceuticalcompositions are administered intravenously. The disclosedpharmaceutical compositions herein can be administered as the soleactive agent or in combination with other pharmaceutical agents such asother agents used in the treatment of Chagas disease in a subject.

The amount of the disclosed nanocarriers or pharmaceutical compositionscomprising the same to be administered is dependent on a variety offactors, including the severity of the condition, the age, sex, andweight of the subject, the frequency of administration, the duration oftreatment, and the like. The disclosed nanocarriers or pharmaceuticalcompositions may be administered at any suitable dosage, frequency, andfor any suitable duration necessary to achieve the desired therapeuticeffect, i.e., to treat Chagas disease. The disclosed nanocarriers orpharmaceutical compositions may be administered once per day or multipletimes per day. Alternatively and preferably, the nanocarriers orpharmaceutical compositions may be administered once per week for atleast 2 weeks. In other examples, the nanocarriers or pharmaceuticalcompositions may be administered once per day, twice per day, or threeor more times per day. The disclosed nanocarrier or pharmaceuticalcompositions may be administered daily, every other day, every threedays, every four days, every five days, every six days, once per week,once every two weeks, or less than once every two weeks. Thenanocarriers or pharmaceutical compositions may be administered for anysuitable duration to achieve the desired therapeutic effect, i.e., treatthe Chagas disease. For example, the nanocarriers or pharmaceuticalcompositions may be administered to the subject for one day, two days,three days, four days, five days, six days, seven days, eight days, ninedays, ten days, eleven days, twelve days, thirteen days, two weeks, onemonth, two months, three months, six months, 1 year, or more than 1year. In some embodiments, the nanocarriers or pharmaceuticalcompositions may be administered for 14 days. In some embodiments, thenanocarriers or pharmaceutical compositions may be administered for 60days. In some embodiments, the pharmaceutical composition or nanocarriermay be administered once per week. In some embodiments, thepharmaceutical composition or nanocarrier may be administered once perweek for 60 days.

Any suitable dose of the disclosed nanocarriers or pharmaceuticalcompositions comprising the same may be used. Suitable doses will dependon the therapeutic agent, intended therapeutic effect, body weight ofthe individual, age of the individual, and the like. In general,suitable dosages of the disclosed nanocarriers or pharmaceuticalcompositions comprising the same may range from about 0.025 mgnanocarrier/kg body weight to 200 mg nanocarrier/kg body weight. Forexample, suitable dosages may be about 0.025 mg/kg, or 0.03 mg/kg, or0.05 mg/kg, or 0.10 mg/kg, or 0.15 mg/kg, or 0.30 mg/kg, to 0.5 mg/kg,or 0.75 mg/kg, or 1.0 mg/kg, or 1.25 mg/kg, or 1.5 mg/kg, or 1.75 mg/kg,or 2.0 mg/kg. In some embodiments, the suitable doses may be 1 mgnanocarrier/kg body weight, or 3 mg/kg, or 5 mg/kg, or 10 mg/kg, or 25mg/kg, or 50 mg/kg, or 75 mg/kg, or 100 mg/kg, or 125 mg/kg, or 150mg/kg, or 175 mg/kg, or 200 mg/kg.

In some embodiments, the pharmaceutical composition or nanocarrier maybe administered intravenously.

The present disclosure also provides in some embodiments methods oftreating Trypanosoma cruzi infection in a subject in need thereof, themethod comprising administering to the subject a therapeuticallyeffective amount a pharmaceutical composition comprising a nanocarriercomprising poly(ethylene glycol)-block-poly(propylene sulfide)copolymer; and a therapeutic agent for treating Chagas disease.

As used herein, the terms “treat,” “treatment,” and “treating” refer toreducing the amount or severity of a particular condition, disease state(e.g., Chagas disease), or symptoms thereof, in a subject presentlyexperiencing or afflicted with the condition or disease state. The termsdo not necessarily indicate complete treatment (e.g., total eliminationof the condition, disease, or symptoms thereof). “Treatment,”encompasses any administration or application of a therapeutic ortechnique for a disease (e.g., in a mammal, including a human), andincludes inhibiting the disease, arresting its development, relievingthe disease, causing regression, or restoring or repairing a lost,missing, or defective function; or stimulating an inefficient process.

The severity and course of a T. cruzi infection is highly variable,based on many factors, including the age at which a person becameinfected, the way in which a person acquired the infection, theparticular virulence of the T. cruzi strain involved in the infectionand the immunogenetics of the individual person. There are two phases ofChagas disease: the acute phase, which occurs shortly after an initialinfection, and the chronic phase, that develops over many years, evendecades. Both phases can be symptom free or life threatening. During theacute phase, which lasts for the first few weeks or months afterinfection, a person often has no symptoms at all, by may havenonspecific symptoms such as fever, fatigue, body aches, headache, rash,loss of appetite, diarrhea, and vomiting. Because these symptoms mayresult from many, more common illnesses, most people do not realize thatthe symptoms are from T. cruzi infection. However, a physician maysuspect Chagas disease, particularly in an area of high diseaseprevalience, if there is also mild hepatosplenomegaly, lymphadenopathyor erythema or swelling at the site of the bite (Chagoma), orpreioribital edema upon conjunctival infection (Romaña's sign). Even ifa person develops symptoms during the acute phase, they usually feelwell within a few weeks, but if the person is not treated withantiparasitic medication, the infection is lifelong. Rarely, youngchildren (less than 5%) die from acute myocarditisormeningoencephalitis. The acute phase also can be severe in people withimmunosuppressed individuals, such as patients taking chemotherapy orthose with advanced HIV infection. During the chronic phase, which canlast for decades or even for the entirety of someone's lifetime, mostpeople have no signs or symptoms of infection. Approximately 30 percentof infected people will eventually develop cardiac complications, whichcan include cardiomegaly, cardiac arrhythmias, heart failure or cardiacsudden death or gastrointestinal complications, which can include anenlarged esophagus (megaesophagus) or colon (megacolon), leading toachalasia and/or intractable constipation.

The term “subject” or “patient” are used herein interchangeably to referto a mammal, preferably a human, to be treated by the methods andcompositions described herein. “Mammals” means any member of the classMammalia including, but not limited to, humans, non-human primates suchas chimpanzees and other apes and monkey species; farm animals such ascattle, horses, sheep, goats, and swine; domestic animals such asrabbits, dogs, and cats; laboratory animals including rodents, such asrats, mice, and guinea pigs; and the like. Preferably, the subject is ahuman. In some embodiments, the subject is a mammal having Chagasdisease or been infected with Trypanosoma cruzi. The term “subject” doesnot denote a particular age or sex. In one specific embodiment, asubject is a mammal, preferably a human. In a suitable embodiment, thesubject is a human having Chagas disease or been infected withTrypanosoma cruzi.

The use herein of the terms “including,” “comprising,” or “having,” andvariations thereof, is meant to encompass the elements listed thereafterand equivalents thereof as well as additional elements. Embodimentsrecited as “including,” “comprising” or “having” certain elements arealso contemplated as “consisting essentially of” and “consisting of”those certain elements.

As used herein, “about” means within 5-10% of a stated concentrationrange or within 5-10% of a stated number.

It should be apparent to those skilled in the art that many additionalmodifications beside those already described are possible withoutdeparting from the inventive concepts. In interpreting this disclosure,all terms should be interpreted in the broadest possible mannerconsistent with the context. Variations of the term “comprising” shouldbe interpreted as referring to elements, components, or steps in anon-exclusive manner, so the referenced elements, components, or stepsmay be combined with other elements, components, or steps that are notexpressly referenced. Embodiments referenced as “comprising” certainelements are also contemplated as “consisting essentially of” and“consisting of” those elements. The term “consisting essentially of” and“consisting of” should be interpreted in line with the MPEP and relevantFederal Circuit's interpretation. The transitional phrase “consistingessentially of” limits the scope of a claim to the specified materialsor steps “and those that do not materially affect the basic and novelcharacteristic(s)” of the claimed invention. “Consisting of” is a closedterm that excludes any element, step or ingredient not specified in theclaim. The phrase “and/or,” as used herein in the specification and inthe claims, should be understood to mean “either or both” of theelements so conjoined, i.e., elements that are conjunctively present insome cases and disjunctively present in other cases. Multiple elementslisted with “and/or” should be construed in the same fashion, i.e., “oneor more” of the elements so conjoined. Other elements may optionally bepresent other than the elements specifically identified by the “and/or”clause, whether related or unrelated to those elements specificallyidentified. Thus, as a non-limiting example, a reference to “A and/orB”, when used in conjunction with open-ended language such as“comprising” can refer, in one embodiment, to A only (optionallyincluding elements other than B); in another embodiment, to B only(optionally including elements other than A); in yet another embodiment,to both A and B (optionally including other elements); etc.

As used herein in the specification and in the claims, “or” should beunderstood to have the same meaning as “and/or” as defined above. Forexample, when separating items in a list, “or” or “and/or” shall beinterpreted as being inclusive, i.e., the inclusion of at least one, butalso including more than one, of a number or list of elements, and,optionally, additional unlisted items. Only terms clearly indicated tothe contrary, such as “only one of” or “exactly one of,” or, when usedin the claims, “consisting of,” will refer to the inclusion of exactlyone element of a number or list of elements. In general, the term “or”as used herein shall only be interpreted as indicating exclusivealternatives (i.e. “one or the other but not both”) when preceded byterms of exclusivity, such as “either,” “one of,” “only one of,” or“exactly one of.”

The present invention has been described in terms of one or morepreferred embodiments, and it should be appreciated that manyequivalents, alternatives, variations, and modifications, aside fromthose expressly stated, are possible and within the scope of theinvention.

The following Examples are offered for illustrative purposes only, andare not intended to limit the scope of the present invention in any way.Indeed, various modifications of the invention in addition to thoseshown and described herein will become apparent to those skilled in theart from the foregoing description and the following examples and fallwithin the scope of the appended claims.

EXAMPLE 1

Introduction

American Trypanosomiasis or Chagas disease (CD) is a vector-bornedisease first described by the Brazilian sanitary physician CarlosChagas, in 1909 (1). After discovering the flagellate protozoanparasite, Trypanosoma cruzi, Chagas was able to deduce the entirecomplex parasite life cycle, clinical symptoms, and social impact of CD(2). At the beginning of the 20th century, CD was considered a ruralendemic disease, strictly associated with the proximity between theinsect vector and humans living in poor housing and sanitary conditionsin Latin America (3). However, in the 21st century, CD has spread tonon-endemic areas, such as Canada, the USA, Europe, Australia, and Japandue to population migrations and the altered proliferation of triatominebugs stimulated by climate change (4-6). As no vaccine is currentlyavailable, 6-7 million people are infected worldwide and approximately14,000 deaths are reported annually in endemic and non-endemic countriesas a consequence of heart failure induced by the T. cruzi infection (7).

Only two hydrophobic nitroimidazole pro-drugs, Benznidazole (BNZ) andNifurtimox (Nfx), have been available to treat T. cruzi-infectedpatients since 1970 (8). Despite the poor bioavailability andpermeability (9), both drugs can reach up to 80% of efficacy when usedduring acute T. cruzi infections. However, the requirement for long-termtreatment and the severe side effects, including neutropenia, nausea,vomiting and diarrhea, weight loss, hypersensitivity skin reactions andhives, may lead to the permanent withdrawal of treatment (10). CDtreatment is still controversial for chronically-infected patients asthe limited efficacy rate of BNZ and Nfx, from 5-20% (11) does notoutweigh the potential risks associated with the treatment. Thisalarming data is reflected in the CD status as a “neglected disease”,which is still overlooked by drug developers as it mostly affects poorpeople in low-income countries (4,12).

More than a century since CD discovery, the search for effective andsafe drugs remains a challenge. As an obligate intracellular parasite,T. cruzi infects many nucleated cells, including macrophages anddendritic cells (DCs) limiting their activation/maturation and theantigen-presenting capacity, as a immune evasion strategy (10).Protected within the host cells, such as myoblasts, parasites divideintensively generating pseudocyst structures into the cytoplasm (13).Thus, drug candidates against CD must present high solubility,permeability, and selectivity to cross the cell membranes to kill theparasite without damaging the host cell (4). With this in mind, theprogress in the nanomedicine field in the last decades, especially inthe development of drug nanocarriers, has drawn attention, as thesesystems are able to enhance therapeutic efficacy by transporting drugstowards the specific intracellular target, thus reducing the toxiceffects and the required drug treatment concentration (14, 15). Since1995, the benefits of nanodrugs have been successfully incorporated intoanticancer therapies, particularly in reducing the toxicity oftraditional treatments (16, 17). Unfortunately, nanotechnology has notyet achieved its maximum drug delivery performance for CD treatmentsince nanocarriers loaded with high doses of antichagasic drugs or thehigh administration frequency of nanocarriers loaded with low-dose drugsseems to be essential for a sufficient trypanocidal effect (12, 18, 19).Some progress, otherwise, have been reached lately. In the case ofpediatric patients, the incorporation of BNZ in self-emulsifying drugdelivery systems represented a therapeutic advance in view of the lowtoxic liquid formulation can collaborate for a more comfortable oraladministration and better intestinal absorption, presenting a similarantichagasic efficacy of free BNZ (20). In terms of CD diagnosis, thenanotechnology based on nano-porous particles was able to concentrate T.cruzi antigens in urine of chagasic HIV-coinfected patients, allowingthe early diagnosis with sensitivity comparable to molecular biologytechniques, as qPCR (21).

Therefore, this study was proposed to deliver BNZ using polymersomesself-assembling from poly (ethylene glycol)-block-poly (propylenesulfide) (PEG-b-PPS) and to evaluate the BNZ-loaded polymersomes(BNZ-PS) efficacy in a murine model of acute CD. Based on our previousstudies, PEG-b-PPS polymersomes (PS) accumulate within DCs andmacrophages (13, 22-25), the primary targets of T. cruzi during acuteinfection (26). Our in vitro studies confirmed the BNZ-PS activityagainst T. cruzi amastigotes and revealed the intracellularcolocalization of BNZ-PS and bioluminescent T. cruzi parasites after amyoblast “in vitro” infection. The efficient delivery of BNZ by PSproved to be better in the CD murine model after only two BNZ-PSinjections, reducing the blood and heart parasitemia at doses 666-foldand 66-fold lower than the required standard dose of free BNZ,respectively. Furthermore, typical signals of BNZ toxicity were notobserved after BNZ-PS treatment.

To the best of our knowledge, this is the first time that such low dosesof BNZ were effective in reducing the parasitemia of T. cruzi-infectedmice. Our findings demonstrate that the efficient delivery of BNZ byPEG-b-PPS polymersomes enables the antichagasic effect of BNZ to beachieved at significantly lower concentrations whilst simultaneouslyavoiding the major BNZ treatment drawback—the systemic toxicity.

Results and Discussion

BNZ nanoparticles. Benznidazole (BNZ), a nitroimidazole with poor watersolubility, has been widely used in clinic for the treatment of T.cruzi. However, therapeutic efficacy requires the administration of highdoses of BNZ to patients on a daily basis, resulting in high risks oftoxicity and side effects (27, 28). Our previous studies havedemonstrated that nanocarriers composed of poly (ethyleneglycol)-block-poly (propylene sulfide) (PEG-b-PPS) could achieve highloading efficiency for diverse small molecules, increase watersolubility, and enhance intracellular delivery (29-32). The PEG-b-PPSnanocarriers are both noninflammatory and non-toxic in mice (25, 33) andnonhuman primates (23). The vesicular nanocarriers, i.e. polymersomes(PS), displayed a superior capacity to target antigen-presenting cells,such as dendritic cells (DCs), and macrophages, in spleen and liver (25,32). To enhance the therapeutic efficacy and decrease off-targettoxicity, the BNZ-loaded PS (BNZ-PS) were achieved by loading BNZ intoPEG-b-PPS PS via the thin-film rehydration method (FIG. 1A). The loadingof BNZ into PS does not change the vesicular structure as verified usingcryogenic transmission electron microscopy (CryoTEM) (FIG. 1B). The sizedistribution of PS and BNZ-PS was determined using dynamic lightscattering (DLS) (FIG. 1C). The hydrodynamic size of BNZ-PS was ˜115 nm,which is comparable to the unloaded PS (Table 1). Zeta potential showedthat the surface charge of BNZ-PS was slightly positive, but effectivelyneutral, in PBS solution (Table 1). The encapsulation efficiency (% EE)and loading efficiency (% LE) of BNZ-PS were ˜31% and ˜1% respectively,as characterized by using liquid chromatography-mass spectrometry(LC-MS) (Table 1, FIG. 5 ).

TABLE 1 Characterization of PS and BNZ-loaded PS in PBS solution (pH =7.4). Average Zeta Encapsulation Loading Name of diameter Polydispersitypotential efficiency efficiency samples (nm) index (PDI) (mV) (%) (%w/w) Polymersomes  120 ± 6.2  0.06 ± 0.01 −1.97 ± 0.46 N/A N/A (PS)BNZ-loaded 114.3 ± 4.1  0.11 ± 0.02   4.92 ± 1.93 ~31 ~1 polymersomes(BNZ-PS)

IC50 for two strains of T. cruzi. The trypancidal effectiveness ofBNZ-PS for Y and Tulauen strain was evaluated in vitro using theresarzurin assay (FIG. 2 a ). The half-inhibitory concentration (IC50)of free BNZ for Y and Tulauan strain trypomastigote was 55.87+−1.39 μM,12.39+−2.41p M respectively. The IC50 of BNZ-PS for Y and Tulauan straintrypomastigote was 56.06+−12.218 μM, 6.28+−0.8 μM respectively.

For Y strain, the amastigote killing effectiveness of BNZ-PS wasevaluated in vitro using counting (FIG. 2 b ). The effectiveness forTulauen strain amastigote killing was evaluated with bioluminescentquantification (FIG. 2 c ). BNZ-PS was significantly more efficient atkilling amastigote both for Y and Tulauen strain, there was a 7-foldreduction in BNZ-PS relative to free BNZ. The IC50 of free BNZ for Y andTulauan amastigote was 30.07+−8.17 μM, 12.47+−3.05 μM respectively.4.404+−

Uptake and intracellular distribution of Benznidazole loadedpolymersomes in T. cruzi infected H9C2 cells. Before investigating theeffect of BNZ-PS, we first tested if the free PS could be efficientlytaken up by the T. cruzi infected cells. For this purpose, the PS wereconjugated with Alexa630, and then incubated with T. cruzi infected H9C2cells for 4 h. As shown in FIG. 3 a , the confocal imaging showed thatfree PS were confirmed to efficiently taken up by H9C2 cells after a 4 hincubation. We further validated the amastigote killing ability ofAlexa630 conjugated PS loaded with BNZ at different BNZ concentrationafter incubated with T. cruzi infected H9C2 cells for 24 hours. As shownin FIG. 3 b , BNZ loaded PS demonstrated stronger amastigote killingability at same BNZ concentration.

The high incidence rate of side effects among T. cruzi-infected patientstreated with BNZ (34,35) is a major issue for this drug therapy againstChagas disease. Although BNZ is better tolerated than Nfx, an average of20% of the patients receiving the standard BNZ doses have to interruptthe treatment schedule due to the occurrence of severe side effects (34,36). As Research and Development of new drugs to treat rare or neglecteddiseases require a high-risk investment for pharmaceutical industries,two alternative approaches have emerged that present a low failure rateand are less time-consuming for industries: the repurposing of drugs andthe modification of effective old drugs to modulate their unsatisfactoryproperties (37). In the last decades, nanotechnology has led to abreakthrough in the development of drug delivery systems, especiallyregarding strategies of controlled drug release and targeted delivery.Therefore, not surprisingly, our results showed that nanoBNZ wassuccessfully applied for the controlled release of BNZ into T.cruzi-infected cells. However, the most important contribution of ourinvestigations for Chagas disease therapy is through the demonstrationof how PEG-b-PPS vesicular nanocarriers, i.e. polymersomes, can optimizethe BNZ delivery, enhancing the antichagasic efficacy, especially in thecardiac tissue of infected mice, minimizing the risk of BNZ toxiceffects.

PEG-b-PPS is a physiologically inert copolymer used to assemblenanocarriers in a variety of shapes depending on the length of eachpolymer chain (22, 38). In this study, PEG-b-PPS was engineered toassemble vesicles loaded with BNZ, a hydrophobic drug, as the highhydrophobicity of the PPS polymer ensures stable BNZ incorporation. PPShydrophobicity and PEG hydrophilicity are responsible for the creationof a highly stable macroamphiphile copolymer. However, when it comes tothe application of nanomaterials against intracellular parasiteinfection, the disruption of nanocarrier stability in the cellularmicroenvironment is essential for effective intracellular drug delivery(39). Thus, although nanoparticles have to be designed to ensure highstability to protect the drug from degradation during long-term storageand to avoid accidental drug release in the patient before reaching theparasitized tissue, intracellular mechanisms must trigger thenanocarrier destabilization for consequent drug release (40-42).

Endocytic pathway is the primary mechanism for the cellular uptake ofnanoparticles smaller than 500 nm (43), as PEG-b-PPS polymersomes.Oxidative enzymes inside the endolysosomal vacuoles, where PEG-b-PPSpolymersomes are localized after endocytosis, promote the oxidation ofsulfide moieties to sulfoxide in PPS block that modifies thehydrophilic-lipophilic balance of PEG-b-PPS copolymer. The oxidationprocess promotes a nanoarchitecture remodeling and consequent drugrelease during the initial stages of oxidation. The oxidation results insmaller amphiphiles blocks that may be inserted into the endosomalmembrane, promoting the endosomal membrane permeabilization andconsequent the escape of PEG-b-PPS vesicles to the cytosol, where thepayload will also be released (30). The escape of nanocarriers towardthe cytosol after endocytosis has been studied as a strategy to protectthe pH-sensitive bioactive molecules from the acidic pH of endolysosomalvacuoles. For this purpose, nanocarriers are prepared from pH-sensitivepolymers able to disrupt endosomal lipid bilayer membranes just inacidic pH, migrating to the cytosol for drug delivery (44).

Polymersomes and the T. cruzi parasite share this same route inside thecell. After invading phagocytic or non-phagocytic mammalian cells, T.cruzi trypomastigotes, are first restricted to the acidic endolysosomalcompartments (i.e. parasitophorous vacuole), where they begin thedifferentiation process into amastigotes. The low pH enhances theactivation of a porin-like protein, Tc-Tox, secreted by theintracellular T. cruzi. Tc-Tox lead to the formation of small pores topromote the fragmentation of endolysosomal vacuoles membrane, resultingin T. cruzi escape to the cytosol, a pH friendly environment, where thedifferentiation is completed (45, 46). Therefore, the colocalization ofthe PEG-b-PPS polymersomes and the parasite in the cytosol of host cellswas the key feature for the choice of this intracellular delivery systemfor BNZ, and hence reason for the outstanding antiparasitic activity ofnanoBNZ. These findings suggest that PEG-b-PPS polymersomes may be asuitable nanocarrier to deliver bioactive molecules against otherpathogenic microorganisms residing freely in the cytosol. Somepathogenic bacteria and other protozoa have developed differentstrategies to escape from the harsh hydrolytic environment of theendolysosomal compartment to reside in the cell cytosol. Some of them,such as Plasmodium spp. (47), Toxoplasma spp. (48), Rickettsia spp.(49), and Mycobacterium spp. (50, 51) are responsible for causing severeand potentially disabling diseases, such as malaria, toxoplasmosis,rickettsiosis, and Hansen's disease and tuberculosis, respectively.

As endocytosis is the most common mechanism of nanoparticle cellularuptake, the colocalization of drug nanocarriers and intracellularparasites inside parasitophorous vacuoles are unquestionable. This isespecially important for intracellular parasites such as Leishmaniaspp., a kinetoplastid parasite completely adapted to survive andreplicate inside acidic endosomal vacuoles (52). The successfulapplication of liposomal Amphotericin B against Leishmania spp. can beattributed to the release of Amphotericin B inside the parasitophorousvacuole, where Leishmania amastigotes reside. However, Amphotericin Bhydrophobicity impairs its diffusion from the phagosome to the cytosol,hinder Amphotericin B reaching the parasites that eventually reside inthe cytosol, outside the endosomal compartments (39). This explains thelimited effectiveness of liposomal Amphotericin B in reducing the T.cruzi parasitic burden, despite the satisfactory Amphotericin B activityagainst extracellular T. cruzi developmental stages (18, 19, 53-55).

To complete its life cycle in the mammalian host, T. cruzi amastigotesdifferentiate once again into trypomastigotes, which are released intothe bloodstream as a consequence of host cell rupture. Interrupting anypoint of the intracellular T. cruzi life cycle can result in theelimination of both amastigotes in the tissues and trypomastigotes inthe bloodstream. Drugs that act predominantly against trypomastigotestend to be less effective during the chronic stage of Chagas diseasewhen the host immune response can control the trypomastigote burdenwhereas dormant amastigotes persist in tissues (56). Thus, although thelow BNZ dose in nanoBNZ is not likely to be active againsttrypomastigotes in the blood mice, the efficient delivery intoparasitized host cells caused a disruption of the parasite life cycle bykilling the intracellular amastigotes, preventing the posteriortransition to trypomastigotes and, consequently, reducing the bloodparasitemia. Additionally, nanoBNZ was demonstrated to be more effectivethan oral BNZ in controlling heart inflammation. It is worth noting thatalthough the autoimmune response may be related to the myocarditis inchronic Chagas disease, the reduction of parasite burden in the hearthas to be considered in the mitigation of cardiac inflammation duringthe acute stage of Chagas disease (57). However, although oral BNZsignificantly reduces the heart parasitemia, as well as the nanoBNZtreatment, the histological analysis revealed that just the nanoBNZ wasable to control cardiac inflammation. Even a concentration of nanoBNZthat did not significantly reduce cardiac parasitemia was competent inreducing cardiac inflammation, suggesting that nanoBNZ has theadditional benefit of ameliorating this symptom regardless of thepresence of parasites in the heart. These findings justify furtherstudies of nanoBNZ as a promising strategy against chronic Chagasdisease.

Whilst in the acute phase of Chagas disease the ability of BNZ inreducing the trypomastigote number in the peripheral bloodstream isundeniable, the limited efficiency in reducing the persistent T. cruziamastigote number in reservoir organs and symptoms of cardiomyopathy arethe reasons for the questionable efficacy of traditional BNZ in thechronic stage (11, 58). Such phenomena can be understood by consideringthe pharmacokinetic properties of the traditional BNZ oral formulation:after intestinal absorption, the low permeation across the cell membrane(55) is responsible for maintaining a high BNZ plasma concentration,although over 40% of the drug is inactive by being bound to plasmaticproteins. The colocalization of trypomastigotes and BNZ in vascularcompartments support the intense BNZ activity against bloodtrypomastigotes (18). As low doses of standard BNZ, such as thosepresent in nanoBNZ, would not show trypanocidal activity (59), ourfindings indicate that nanoBNZ activity is a consequence of theimprovement of permeation promoted by the PEG-b-PPS nanocarrier.

The BNZ sustained release must also be considered as an essential aspectof the nanoBNZ treatment. Sustained drug release for up to 12 days hasalready been reported for PEG-b-PPS nanocarriers in a previous study asa function of the PPS chain length, and it depends on drug partitioningfrom the hydrophobic PPS phase into water (29, 60). As BNZ is consideredpractically insoluble in water (9), its slow diffusion from PPS to thecellular microenvironment may have contributed to the successfulantichagasic effect of only two nanoBNZ administrations during the 14days of treatment. The low BNZ half-life in mice (t_(1/2)=2 h) supportedby a high metabolic rate, including the first-pass metabolism after oraladministration, and subsequent low bioavailability, is the reason forthe administration of high BNZ daily doses (9). In humans, a greaterhalf-life (t/2=12 h) (18) and a lower metabolic rate allow a lower dosein comparison to those given to mice, but still, daily doses arenecessary to keep a high BNZ plasma concentration and consequently ahigh permeation cell rate to reach intracellular amastigotes (39).Although the daily administration increases the trypanocidal effect ofBZN, it also enhances the systemic BNZ metabolism (18) resulting intoxic effects, the major drawback about BNZ treatment. As a prodrug, BNZmust be metabolized by T. cruzi type I nitroreductases, which are absentin humans, in order to become active. However, BNZ can also bemetabolized by mammalian cells through type II nitroreductases,producing toxic metabolites for the host, such as reactive oxygen andnitrogen species (18). High BNZ dose regimens and the accumulation ofBNZ after many days of treatment may be responsible for the severity ofsystemic toxic effects (61, 62). Thus, in terms of toxicity, ourfindings corroborate that low doses of BNZ and a reduced number of dosesas well do not cause hepatotoxic effects and weight loss, which arecommon toxic signals from oral BNZ treatment in T. cruzi infected mice.Therefore, the nanoBNZ competence in promoting a sustained BNZ releasein mice may represent a remarkable advantage over the traditional BNZformulation, especially concerning the BNZ toxicity.

In conclusion, the efficiency of nanoBNZ in minimizing the heartinflammation, the cardiac amastigote burden, and the trypomastigoteparasitemia, without causing the typical toxic signals, reinforces theidea that overcoming the BNZ pharmacokinetic issues to improve thecellular biodistribution in solid organs is critical for optimizing theantichagasic effect of low BNZ doses (11, 63). In a broader field,PEG-b-PPS polymersomes should be explored as a drug delivery systemagainst other intracellular parasites since their multifacetedproperties allow the encapsulation of hydrophobic and hydrophilic drugssimultaneously (22), as well as promoting the payload delivery intovacuoles and cytosol.

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Materials and Methods of Example 1

Synthesis of PEG-b-PPS Copolymers and Loading of Benznidazole (BNZ) intoPolymersomes PS (PS).

Polymersomes were prepared by the controlled self-assembly of poly(ethylene glycol)-bl-poly (propylene sulfide) (PEG-b-PPS) blockcopolymers with the 25%-45% molecular weight of hydrophilic PEG fractionin the total block copolymer. PEG-b-PPS block copolymers weresynthesized as previously described (1). Briefly, the anionicring-opening polymerization of propylene sulfide initiated by PEGthioacetate and end-capped with PEG mesylate. The obtained blockcopolymers (PEG₁₇-PPS₆₀-PEG₁₇) were purified by precipitation inmethanol, and then characterized through NMR and gel permeationchromatography (GPC) (ThermoFisher Scientific). The loading ofbenznidazole (BNZ) into polymersomes (PS) was performed through thinfilm rehydration method in PBS as described previously (1, 2). Briefly,30 mg of the copolymer (PEG₁₇-PPS₆₀-PEG₁₇) with or without 1.5 mg of BNZwas dissolved in 150 μL Tetrahydrofuran (THF) within 1.8 mL clear glassvials (ThermoFisher Scientific) and placed under vacuum to remove thesolvent. The resulting thin films were dehydrated in sterile PBS (1 mL)under shaking at 1500 rpm for 48 h. The BNZ-PS were purified to removefree BNZ by Zeba Spin Desalting Columns (7K MWCO, ThermoFisherScientific).

Characterization of BNZ-PS

The liquid chromatography-mass spectrometry (LC-MS) analysis wasperformed on a Bruker AmaZon-X. Samples were chromatographed on aHypersil BDS C18 column (2.4 mm particle size, 2.1×50 mm) (ThermoFisher) at 40° C. The separation was achieved by a gradient of waterwith 0.1% formic acid (eluent A) and acetonitrile with 0.1% formic acid(eluent B) with a flow rate of 0.3 mL min-1. Detection was performed at324 nm and the injection volume was 2 μL. The gradient starts at 40% Bfor 1 min, increases to 100% B in 4 min, holds at 100% B for 5 min,decreases to 90% B in 0.1 min, and holds at 90% B for 1.9 min. Thestandard calibration solution of BNZ was prepared in acetonitrile/water(95:5 v/v) ranging from 3.125 to 100 mg/mL. BNZ-PS samples weredissolved in acetonitrile/water (95:5 v/v) and then filtered through 0.2mm membrane (ThermoFisher Scientific). The loading efficiency (% LE) ofthe BNZ-PS was determined by the percentage of the loaded weight of BNZin the total weight of BNZ-PS. The encapsulation efficiency (% EE) ofthe BNZ-PS was calculated by the percentage of BNZ weight loaded intothe PS in the initial BNZ weight added. The size distribution and zetapotential of PS and BNZ-PS (1 mg/mL) were characterized by ZetasizerNano-ZS (Malvern Instruments, UK) using a 4 mW He—Ne 633 laser. Themorphology of PS and BNZ-PS was determined by cryo transmission electronmicroscopy (CryoTEM) as described previously (3). In brief, 200 mesh Cugrids with a lacey carbon membrane (EMS Cat #LC200-CU-100) wereglow-discharged in a Pelco easiGlow glow discharger (Ted Pella Inc.,Redding, Calif., USA) using an atmosphere plasma generated at 15 mA for15 seconds with a pressure of 0.24 mbar. PS and BNZ-PS samples (4 μL, 10mg/mL in PBS) were pipetted onto the grid and blotted for 5 s with ablot offset of +0.5 mm, followed by immediate plunging into liquidethane within a FEI Vitrobot Mark III plunge freezing instrument (ThermoFisher Scientific, Waltham, Mass., USA). The plunge-frozen grids werekept vitreous at −180° C. in a Gatan Cryo Transfer Holder model 626.6(Gatan Inc., Pleasanton, Calif., USA) while viewing in a JEOL JEM1230LaB6 emission TEM (JEOL USA, Inc., Peabody, Mass.) at 100 keV. Imagedata were collected by a Gatan Orius SC1000 CCD camera Model 831 (GatanInc., Pleasanton, Calif., USA). The images were processed and analyzedusing ImageJ. To investigate the storage stability, BNZ-PS suspension(30 mg/mL in PBS) was kept in sealed tubes and maintained at 4° C. Atdifferent time points (0, 1, 4, 8, 15, and 45 days), the released orunloaded BNZ was removed by using Zeba Spin Desalting Columns (7K MWCO,ThermoFisher Scientific). The percentage of loaded BNZ in PS atdifferent time points (compared to day 0) was determined by LC-MSaccording to the above-mentioned protocols.

Cells, Cell Culture and Parasite Purification

The Y strain of T. cruzi was used for all experiments. Epimastigoteswere cultured using standard methods and tissue culture amastigotes andtrypomastigotes were produced by the addition of log-phase epimastigotesto cultured H9C2 rat myoblast cells, which contain small numbers ofmetacyclic trypomastigotes capable of initiating mammalian cellinfection. After several days of culture in H9C2 cells, amastigotes andtrypomastigotes were purified for use in IC50 determination experiments.

IC50 Determination

For the evaluation of anti-amastigote activity of T. cruzi Y strain,50,000 H9C2 cells were seeded in chamber slides (Nunc Lab-Tek II,ThermoFisher Scientific). After 24 h, at 37° C. and 5% CO₂, H9C2 cellswere infected with T. cruzi Y strain trypomastigotes at a 1:5host-to-parasite cell ratio for additional 24 h and washed. Then theplate was incubated with different dilutions of BNZ and BNZ-PS. Themedium was replaced every 24 h and the slide was fixed and stained withGiemsa solution (Richard-Allan Scientific Giema Stain, ThermoFisherScientific) after 48 h. The number of amastigotes/100 H9C2 cells wascalculated for each chamber.

For the evaluation of anti-amastigote activity of T. cruzi Tulahuenstrain, 5000 H9C2 cells were seeded in a 96 well clear bottom tissueculture plate (Thermo Scientific). After 24 hours, the culture wasinfected with Luc-mNeonGreen Tulahuen strain trypomastigotes at a 1:5host-to-parasite cell ratio for 24 h. Free trypomastigotes were washedoff and infected cells were incubated with different dilutions of BNZ,BNZ-PS, and PS for 48 h. The medium was replaced every 24 h. At 48 h, 10μL of 15 mg mL⁻¹ luciferin were added into each well, and the luciferaseintensity was measured using a IVIS Spectrum (Caliper Life Science) andthe ROI was analyzed with Softmas Pro. Exposure time varied from 5 s to15 s depending on signal intensity.

Anti-Trypomastigote Activity

Resazurin method was used to evaluate in vitro anti-trypanosoma activityagainst Y trypomastigotes. 1×10⁷ trypomastigotes mL⁻¹ were incubated in96-well plates containing serial dilution of BNZ and BNZ-PS in RPMI 2640medium with 5% FBS, penicillin (100 μL/mL), streptavidin (100 μL/mL) andL-glutamine (2 mM). For BNZ, the stock solution (1024 mM) was preparedin DMSO and made serial dilution to 1024 μM, 512 μM, 256 μM, 128 μM, 64μM, 32 μM, 16 μM, 8 μM, 4 μM. For BNZ-PS, the stock solution (BNZ 1170μM) was made serial dilution to 256 μM, 128 μM, 64 μM, 32 μM, 16 μM, 8μM, 4 μM, 2 μM, 1 μM, 0.5 μM. After incubation for 24 h, at 37° C. and5% CO₂, 10 μL of alamarBlue Cell Viability reagent (Invitrogen) wereadded in each well, then incubate at 37° C. for 4 h. The fluorescencewas measure on a microplate reader (BMG Labtech) at 560/590 nm toevaluate trypomastigote viability. A log concentration vs response curvewas generated and the BNZ IC50 was calculated in GraphPad Prism 7.0.

Nanoparticle Uptake

H9C2 cells were seeded in chamber slides (Nunc Lab-Tek II, ThermoScientific) for 24 h followed by the infection with Luc-mNeonGreenTulahuen strain trypomastigotes at 1:5 host to parasite cell ratio for24 h. Free trypomastigotes were washed off and infected H9C2 cells wereincubated with Alexa630 fluorescent labeled polymersomes for 24 h.Chamber slides were washed with PBS 5 times and stained with CellMaskDeep Red Plasma Membrane Stain (Invitrogen) for 5 min and DAPI for 20min. Leica confocal microscope were used to imaging the slide.

Mouse Infections

All animal protocols were reviewed and approved by the InstitutionalAnimal Care And Use Committee of Cedars Sinai Medical Center (Protocol7053). Female BALB/c mice (8-12 weeks of age) were purchased fromJackson Laboratories and on a 12-h dark-light cycle at 22±3° C. Mice hadaccess to food and water ad libitum. T. cruzi trypomastigotes used forinfections were first passaged through female SCID mice (Jackson Labs).2×10³ in vitro derived trypomastigotes of Y strain (genotype TcII) in0.2 ml PBS were first inoculated in SCID mice via i.p. injection.Peripheral blood parasitemia was determined by Brener methods. When SCIDmice parasitemia reached to 1×10⁸ parasites ml⁻¹, infected blood fromSCID mice was harvested and adjusted to 2×10⁴ blood derivedtrypomastigotes (BTs) mL⁻¹. Balb/c mice were infected with 2×10³ BTs viai.p. injection. Parasitemia of Y strain-infected mice was determinedevery other day by trypomastigotes quantification in 3 μL of bloodsamples obtained from the saphenous vein.

BNZ and BNZ-PS Therapy

For drug treatments, BNZ-PS was prepared as mentioned above and BNZ(Sigma-Aldrich) was prepared from powder at 22 mg mL⁻¹ in 5%methylcellulose. After confirmation of the infection (seven dpi), 30mice were randomized in to 6 equal groups as follow: 1) untreatedcontrol, 2) mice treated with 0.3 mg/mL of polymersome (PS) i.v., 3)mice treated with BNZ 100 mg/kg body weight for 14 days p.o., 4) micetreated with BNZ loaded-PS at a BNZ dose of 1.5 mg/kg body weight onceevery seven days for a total of two doses i.v., 5) mice treated withBNZ-PS at a BNZ dose of 0.15 mg/kg body weight once every seven days fora total of two doses i.v., 6) mice treated with BNZ-PS at a BNZ dose of0.03 mg/kg body weight once every seven days for a total of two dosesi.v. At 25 dpi, all infected animals were euthanized under deepanesthesia. Blood and organs were collected for further analysis.

Tissue Parasite Load

Organs and tissues were harvested then snap frozen on dry ice. DNA wereextracted using QIAamp DNA Mini Kit (Qiagen) following themanufacturer's instruction. To make the standard for parasite burdenquantification, 25 mg of skeletal muscle, liver, heart or 10 mg ofspleen tissue of non-infected mouse were mixed with 1×10⁷ T. cruzitrypomastigotes. Total DNA was extracted, and the concentration wasadjusted to 50 ng/μL. The standard curve was established from serialdilution of the sample range from 1×10⁷ to 1×10⁻¹ parasite equivalence.Real-time PCR reactions were carried out using the QuantStudio 5(ThermoFisher Scientific) machine. PCR reactions contained 50 ng of DNA,0.5 μL of primers TCZ-F 5′-GCTCTTGCCCACAMGGGTGC-3′ (SEQ ID NO.: 1) andTCZ-R 5′-CCAAGCAGCGGATAGTTCAGG-3′ (SEQ ID NO: 2), and 10 μL of EXPRESSSYBR GreenER™ qPCR Supermix (Invitrogen) in a final volume of 20 μL.Reactions were run in triplicate on as follow: 50° C. for 2 min and 40cycles of 95° C. for 10 s, 55° C. for 15 s, 72° C. for 5 s. Mousespecific GAPDHf and GAPDHr were used as internal control.

Histopathological Studies

Heart was obtained from all groups, fixed in 10% buffered formalin for15 h and embedded in paraffin. Five micrometer sections were stainedwith Hematoxylin & Eosin (H&E), Masson's Trichrome and Giemsa. Theinflammatory index was derived by quantifying the total number of nucleipresent in 10 randomly selected microscopic fields of each H&E stainedsections. All slides were scanned using Aperio Scanscope AT scannerscanner, images were taken with ImageScope software and analyzed usingImageJ software Windows 64 by an investigator blinded to the groups.

Assessment of the Toxicity of BNZ and BNZ-PS In Vivo

25 healthy Balb/c mice was randomized into the following groups: 1)untreated control, 2) mice treated with 0.3 mg/mL of PS i.v., 3) micetreated with BNZ 100 mg/kg body weight for 14 days p.o., 4) mice treatedwith BNZ-PS at a BNZ dose of 1.5 mg/kg body weight once every 7 days fora total of two doses i.v., 5) mice treated with BNZ-PS at a BNZ dose of0.15 mg/kg body weight once every 7 days for a total of two doses i.v.Mice weight was recorded during the treatment course. At day 15, micewere euthanized and serum and liver were collected. Serums (Sera) weresent out to central lab (IDEXX BioResearch) to measure alanineaminotransferase (ALT/SGPT), aspartate aminotransferase (AST/SGOT), bileacid, bilirubin, blood urea nitrogen (BUN), creatinine,gamma-glutamyltransferase (GGT).

Statistical Analysis

Numerical results of in vitro assays were expressed as theaverage±standard deviation (SD). Individual animals were used as theunit of analysis for in vivo and ex vivo experiments. Animal group sizewas determined empirically. One-way ANOVA and Tukey's multiplecomparisons test were used in GraphPad Prism v.7 to evaluate groupsdifference. The level of significance is presented by *p<0.05.

REFERENCES FOR MATERIALS AND METHODS

-   1. Yi S, Zhang X, Sangji M H, Liu Y, Allen S D, Xiao B, et al.    Surface Engineered Polymersomes for Enhanced Modulation of Dendritic    Cells During Cardiovascular Immunotherapy. Advanced Functional    Materials. 2019; 29(42):1904399.-   2. Yi S, Allen S D, Liu Y-G, Ouyang B Z, Li X, Augsomworawat P, et    al. Tailoring Nanostructure Morphology for Enhanced Targeting of    Dendritic Cells in Atherosclerosis. ACS Nano. 2016;    10(12):11290-303.-   3. Yi S, Karabin N B, Zhu J, Bobbala S, Lyu H, Li S, et al. An    Injectable Hydrogel Platform for Sustained Delivery of    Anti-inflammatory Nanocarriers and Induction of Regulatory T Cells    in Atherosclerosis. Frontiers in Bioengineering and Biotechnology.    2020; 8:542.

We claim:
 1. A pharmaceutical composition for treating Chagas diseasecomprising: a. a nanocarrier comprising: a poly(ethyleneglycol)-block-poly(propylene sulfide) copolymer; and a therapeutic agentfor treating Chagas disease selected from the group consisting ofN-benzyl-2-(2-nitro-1H-imidazol-1-yl)acetamide (Benznidazole),N-(3-Methyl-1,1-dioxido-4-thiomorpholinyl)-1-(5-nitro-2-furyl)methanimine(Nifurtimox), 1-Methyl-2-{[4-methylsulfanyl)phenoxy]methyl}-5-nitro-1H-imidazole (Fexinidazole),4-[4-[4-[4-[[(3R,5R)-5-(2,4-difluorophenyl)tetrahydro-5-(1H-1,2,4-triazol-1-ylmethyl)-3-furanyl]methoxy]phenyl]-1-piperazinyl]phenyl]-2-[(1S,2 S)-1-ethyl-2-hydroxypropyl]-2,4-dihydro-3H-1,2,4-triazol-3-one(Posaconazole), cysteine protease inhibitors, parasite proteasomeinhibitors such asN-[4-fluoro-3-(6-pyridin-2-yl-[1,2,4]triazolo[1,5-a]pyrimidin-2-yl)phenyl]-2,4-dimethyl-1,3-oxazole-5-carboxamide;and b. one or more pharmaceutically acceptable excipients; wherein thetherapeutic agent is formulated at a range of 0.025 mg/kg to 100 mg/kg.2. The pharmaceutical composition of claim 1, wherein the therapeuticagent is N-benzyl-2-(2-nitro-1H-imidazol-1-yl)acetamide.
 3. Thepharmaceutical composition of claim 1, wherein the molar ratio oftherapeutic agent: poly(ethylene glycol)-block-poly(propylene sulfide)copolymer is 0.001% to 50%.
 4. The pharmaceutical composition of claim1, wherein the poly(ethylene glycol)-block-poly(propylene sulfide)copolymer has a PEG weight fraction of 0.25 to 0.45.
 5. Thepharmaceutical composition of claim 1, wherein the poly(ethyleneglycol)-block-poly(propylene sulfide) copolymer has a PEG weightfraction of 0.36.
 6. The pharmaceutical composition of claim 1, whereinthe poly(ethylene glycol)-block-poly(propylene sulfide) copolymer is apolymersome.
 7. The pharmaceutical composition of claim 1, wherein thepoly(ethylene glycol)-block-poly(propylene sulfide) copolymer is ahydrophobic core micelle.
 8. The pharmaceutical composition of claim 1,wherein the therapeutic agent is formulated at a range of 0.025 mg/kg to2 mg/kg.
 9. The pharmaceutical composition of claim 1, wherein thepharmaceutically acceptable excipient is for intravenous administration.10. A formulation for intravenous administration comprising thepharmaceutical composition of claim
 9. 11. A polymersome for treatingChagas disease comprising: a poly(ethylene glycol)-block-poly(propylenesulfide) copolymer; and a therapeutic agent for treating Chagas diseaseselected from the group consisting ofN-benzyl-2-(2-nitro-1H-imidazol-1-yl)acetamide (Benznidazole),N-(3-Methyl-1,1-dioxido-4-thiomorpholinyl)-1-(5-nitro-2-furyl)methanimine(Nifurtimox),1-Methyl-2-{[4-methylsulfanyl)phenoxy]methyl}-5-nitro-1H-imidazole(Fexinidazole),4-[4-[4-[4-[[(3R,5R)-5-(2,4-difluorophenyl)tetrahydro-5-(1H-1,2,4-triazol-1-ylmethyl)-3-furanyl]methoxy]phenyl]-1-piperazinyl]phenyl]-2-[(1S,2S)-1-ethyl-2-hydroxypropyl]-2,4-dihydro-3H-1,2,4-triazol-3-one(Posaconazole), cysteine protease inhibitors, parasite proteasomeinhibitors such asN-[4-fluoro-3-(6-pyridin-2-yl-[1,2,4]triazolo[1,5-a]pyrimidin-2-yl)phenyl]-2,4-dimethyl-1,3-oxazole-5-carboxamide.12. The polymersome of claim 11, wherein the therapeutic agent isN-benzyl-2-(2-nitro-1H-imidazol-1-yl)acetamide.
 13. The polymersome ofclaim 11, wherein the molar ratio of therapeutic agent: poly(ethyleneglycol)-block-poly(propylene sulfide) copolymer is 0.001% to 50%. 14.The polymersome of claim 11, wherein the poly(ethyleneglycol)-block-poly(propylene sulfide) copolymer has a PEG weightfraction of 0.25 to 0.45.
 15. The polymersome-of claim 11, wherein thepoly(ethylene glycol)-block-poly(propylene sulfide) copolymer has a PEGweight fraction of 0.36.